1. Field of the Invention
The present invention relates to an automated, portable, traffic control device designed to replace a flagman who is usually responsible for directing traffic safely around obstructions which potentially bring opposing traffic into conflict.
2. Introduction and Description of Related Art
Flagmen are a common sight along roadways near the site of accidents or road construction that block a lane in the road that is normally open to traffic. On two lane roads especially, when an entire lane is blocked by an accident, road or other construction, or a tree trimming operation, and opposing traffic has to use the same lane, a flagman is positioned at each approach to the site of the blockage. The flagmen are in communication with each other via two-way radios or using hand signals, and each flagman carries a handheld sign with the word "stop" on one side and "slow" on the other. When one flagman displays the word "stop", i.e. the stop sign side of his handheld sign, the other flagman displays the word "slow" allowing traffic to safely proceed through the single open lane in a first direction. Periodically, the flagman displaying "slow" will switch to displaying "stop", and he/she will inform the other flagman, via the two-way radio or using hand signals, of the change to a "stop" display and of the description of the last vehicle that was allowed to proceed through the open lane. The other flagman will then switch to a "slow" display once the last vehicle clears the open lane, allowing traffic in the opposite direction to proceed safely through the open lane. This process is periodically repeated until the obstruction is cleared from the closed lane.
One drawback of the foregoing arrangement is that a sufficient number of trained personnel may not immediately be available, at an accident scene for example, to safely direct traffic around an obstruction. Also, the use of flagmen with handheld signs is labor intensive and a substantial monetary savings could be realized if the flagman with a handheld sign could be replaced by an inexpensive automated flagman.
Many devices for temporarily directing traffic around construction zones have been proposed in the prior art. However, these devices are generally rather large and are mounted on specialized trailers, thus requiring a vehicle to tow these devices to the location where they are to be used. The logistic difficulties in deploying the prior art signs makes them more suitable for situations where temporary traffic control is needed for relatively long durations. Also, the prior art signs are rather expensive with the result that only local or state governments, that have constant need for such devices, can justify the expense of buying the prior art devices. A construction crane operator or an excavating contractor, for example, who may occasionally have need for a traffic control device, could not justify the expense of purchasing the prior art devices. Therefore, the need persists in the art for a portable automated flagman that is small enough to be carried in emergency vehicles and construction machinery at all times, and that is sufficiently inexpensive such that users with only occasional need for traffic control devices can justify the purchase of the portable automated flagman.
Examples of the prior art traffic control devices alluded to above are seen in U.S. Pat. No. 4,992,788, issued to Rudolf P. Arndt on Feb. 12, 1991, U.S. Pat. No. 4,857,921, issued to William B. McBride et al. on Aug. 15, 1989, and U.S. Pat. No. 3,046,521, issued to Edward G. Cantwell et al. on Jul. 24, 1962. Arndt discloses a traffic control trailer with two sets of three-color traffic signals, one of which is height adjustable using hydraulic cylinders. McBride et al. also disclose a traffic control trailer with two sets of three-color traffic signals. Similarly, Cantwell et al. disclose a wheeled base which supports red and green traffic control lights.
U.S. Pat. No. 3,729,706, issued to George P. Hein on Apr. 24, 1973, discloses a remotely controlled flagging unit with a wheeled support. Remote communication with the flagging units is established through wires. Each flagging unit has a three-color traffic control light, a closed circuit television camera, and a speaker. The Hein device seems too bulky to be conveniently carried by an emergency vehicle such as a police cruiser.
U.S. Pat. No. 3,435,412, issued to Albert H. Bohrer, Sr. on Mar. 25, 1969, discloses an internally lighted transparent stop sign. U.S. Pat. No. 2,907,998, issued to Frank E. Conly on Oct. 6, 1959, and U.S. Pat. No. 2,669,705, issued to William Joseph Wheatland Collins on Feb. 16, 1954, disclose collapsible, portable signal lights for use by disabled vehicles to warn other drivers of the presence of the disabled vehicle on the road.
U.S. Pat. No. 2,829,362, issued to Frank Terrill on Apr. 1, 1958, discloses a remote controlled, portable traffic light having a stop light and a go light. Terrill uses radio control to remotely control the traffic light. U.S. Pat. No. 2,462,343, issued to Adolph J. Wohlgemuth on Feb. 22, 1949, discloses a remote control system for multiple street lights from a central location. The Wohlgemuth patent does not relate to portable devices.
The book "101 Unuseless Japanese Inventions--The Art of Chindogu," by Kenji Kawakami, Copyrighted in 1995, shows a handheld signal light with three red lights designed to cosmetically resemble a standard three-color traffic signal.
None of the prior art cited above show a remote controlled sign that rotates to selectively display the words "stop" or "slow". None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.